The Global System for Mobile Communication (GSM) is a standard for digital wireless communications. GSM has different services, such as voice telephony. The Subscriber Identity Module (SIM) inside GSM phones was originally designed as a secure way to connect individual subscribers to the network but is nowadays becoming a standardized and secure application platform for GSM and next generation networks.
In the GSM system, Mobile Station (MS) represents the only equipment the GSM user ever sees from the whole system. It actually consists of two distinct entities. The actual hardware is the Mobile Equipment (ME), which consists of the physical equipment, such as the radio transceiver, display and digital signal processors. The subscriber information is stored in the Subscriber Identity Module (SIM), implemented as a Smart Card.
In addition to voice telephony, today's second-generation GSM networks deliver high quality and secure mobile voice and data services (such as SMS/Text Messaging) with full roaming capabilities across the world.
In mobile networks people can be contacted by calling to their mobile telephone number or by sending to that number a so called short message by e.g. making use of the Short Message Service (SMS). Short Message Service (SMS) is the transmission of short text messages to and from a mobile phone, fax machine and/or IP address. SMS messages must be no longer than 160 alphanumeric characters and contain no images or graphics. The point-to-point Short message service (SMS) provides a means of sending messages of limited size to and from GSM mobiles. Detailed information can be found in the ETSI standard GSM 03.40 Version 5.3.0.
The basic network structure of the SMS service comprises two entities, which may receive or send messages being the endpoints between which the SMS message is sent. The entity can be located in a fixed network, a mobile station or an internet protocol network.
Messages to and from mobile stations are received by a Short Message Service Center (SMSC), which then directs it to appropriate mobile device if the message is to be sent to a mobile station or it must generally direct it to a recipient.
There are many cases where an operator wants to download certain data to all its subscribers, such as different service downloads and Public Land Mobile Network (PLMN) updates. Examples of such updates are amending of the service center number when sending SMS messages, change of a PLMN to influence on the roaming, change of service provider name, settings for WAP or e-mail, telephone list updates and sending advertisements through SMS. The downloading is handled in batches where data is targeted to a certain group of cards in the form of large Over-the-Air (OTA) downloads of data to (U)SIM cards.
GSM has no broadcasting capability for broadcasting data, but must rely on a batch of single casts, where each receiver must be targeted individually, which sets great demand on the delivery system in terms of capacity and throughput.
When an operator wants to make a batch download, data will be sent to each receiver, which will create large queues in all intermediate parts of the network, such as in e.g. SMS-C, since such download messages usually have to be divided in several successive messages. The OTA downloads delivered to the customers might be quite large, ranging from 5 up to 30 SMs per subscriber, if a batch targets 100,000 subscribers. If e.g. a quarter of these are inactive, the number of queued SMs will be somewhere between 125,000 and 750,000 which will quite seriously affect the performance for other traffic. If the receiver is inactive the queues will be full for some time, degrading the performance until the payload is expired or the receiver is turned on.